Two coil,triple point ignition system



May 5, 1970 F. M. UHLAND TWO COIL, TRIPLE POINT IGNITION SYSTEM FiledMarch 1.5, 1968 Floyd M. Uh/and INVENTOR. Mm wig M 3m United StatesPatent 3,510,670 TWO COIL, TRIPLE POINT IGNITION SYSTEM Floyd M. Uhland,73 Center Granview, Quincy, II]. 62301 Filed Mar. 15, 1968, Ser. No.713,519 Int. Cl. H01h 1/6'0 US. Cl. 307- '7 Claims ABSTRACT OF THEDISCLOSURE The present invention relates to a battery ignition systemfor internal combustion engines and more particularly to an ignitiondistributor assembly.

Conventional automotive systems include an ignition coil primary windingserially connected between the voltage source and a normally closedpoint assembly through which an energizing circuit is completed. Uponperiodic breaking of the points, due to urging of a rotating distributorcam, the circuit is broken thereby causing deenergization of the primarywinding which in turn rapidly reduces the flux of the primary winding.This rapid flux reduction induces a large voltage in the secondary ofthe ignition coil which is distributed to the spark plugs of theinternal combustion engine through a rotor assembly in a mannerwell-known in the art. As will be appreciated, opening of the pointscreates a large potential gap which ionizes the air therebetween causingarcing and unidirectional transfer of metal from one point to the other.Such action occurs at a high frequency until deterioration of the pointsrender them useless because of oxidized metal deposits on the contactsurface of one of the point contacts. A common expedient to preventarcing across the gap is provided by connecting a capacitor across thepoints. Thus, upon breaking of the points, current from the energizingprimary winding charges the capacitor instead of arcing across thepoints. Although it is theoretically possible to eliminate this arcingby employment of perfectly complementing ignition coil and capacitorcharacteristics, in practice such is difficult to achieve over anextended period of time, due to variation in electrical componentcharacteristics. The art is replete with attempts to minimize thisaforementioned point deterioration problem. One solution to the problemenompasses a dual point construction being actuatable by a common cam.The art combines these dual points in a multitude of combinations andpermutations with ignition coils and capacitors in order to reduce thepotential developed across the points when opened or to reduce thenumeral of cycles per engine revolution.

In accordance with the present invention the foregoing problems aredealt with by reversing the arcing current to prevent unidirectionaltransfer of metal from point to point and thereby avoid accumulation ofmetallic deposits on the contact surface.

In summary, the present invention achieves the latter mentioned objectby providing a dual point assembly operatively driven by a common cam.Each set of points in the dual point assembly opens alternately therebyachieving a total number of actuations during a single rotation of thecam equal in number to the cylinders in the internal combustion engine.A third assembly is provided and is actuatable in response to a secondcam causing a number of third point assembly actuations per revolutionof the cam equal in number to the cylinders of the englne. These lattermentioned points are connected to the dual point assembly thus providingthe third point assembly with an alternating ground connection wherebyarcing current is alternately conducted in opposite directions acrossthe third point assembly. Thus, the present invention establishes asystem which prevents unidirectional transfer of metal from one point tothe other to prolong the useful life of an ignition circuit breakerpoint assembly with an attendant financial saving and maintenanceconvenience.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIG. 1 is a cutaway elevational view exposing the interior of adistributor.

FIG. 2 is a horizontal sectional view taken along a plane passingthrough section line 22 of FIG. 1.

FIG. 3 is a horizontal sectional view taken on a plane passing throughsection 3-3 of FIG. 1.

FIG. 4 is an electrical schematic diagram of the present invention.

Referring specifically to the drawings, and more particularly to FIG. 1,reference numeral 10 generally denotes the three-point contact breakermechanism of the present invention disposed within a distributor housing12. The three-point mechanism 10 comprises a first dual point assemblygenerally denoted by reference numeral 14 and a single point assembly 28cooperating therewith as hereinafter explained. FIG. 3 illustrates theorientation of points in assembly 14 with relation to a distributor cam16 suitably keyed to a rotating distributor shaft 18. By way of example,the present invention is associated with an 8-cylinder engine for whichthe cam is contoured. However, it will be apparent that the cam could beredesigned so as to operate successfully with an internal combustionengine with a number of cylinders other than eight. The peripheralsurface of the cam 16 in the illustrated embodiment includes fourequally spaced high points or lobes indicated by 20. A dwell surface 22connects adjacent high points. A first contact point assembly 24 isdisposed in relation to the cam 16 so that its cam follower 25 isdisplaced from the cam follower 27 of a second point assembly 26. Thus,when either cam follower 25 or 27 is positioned upon a high point 20 ofthe cam 16, the other cam follower will contact a dwell portion of thecam medially between two other high points. As will be appreciated, thisarrangement will permit alternative actuation of the point assemblies 24and 26 for firing S-engine cylinders during one revolution of cam 16.

Referring once again to FIG. 1 of the drawings, it will be noted that athird point assembly 28 is disposed in axially spaced relation to theaforementioned dual point assembly 14. As FIG. 2 clearly shows, thelatter mentioned point assembly resembles a conventional single pointassembly and is operatively actuated by a cam 30 having eight highpoints 32 equally spaced around the perimeter of the cam. In the presentinvention, cam 30 is disposed in spaced coaxial relation to cam 16 andis suitably keyed to the shaft 18 in fixed angular relation to cam 16.Attention is directed to the single point assembly 28 which illustratesan insulated connection to the point 68 instead of conventionalgrounding of said points to a grounded base plate for reasons to becomehereinafter apparent.

Attention is directed to FIG. 4 which illustrates the variousconnections to circuit components of the present invention. Ashereinbefore described, cam 16 actuates the first point assembly 24having a first contact 38 thereof grounded. The second contact 36thereof is connected to one side 40 of a capacitor 42, the opposite sideof the capacitor being grounded. Connection between the contact 36 andcapacitor 42 defines a primary winding 46. This primary winding isincluded in a conventional ignition coil (not shown). The opposite end48 of the primary winding is connected to a DC. souce of voltage 50. Asfurther illustnated in FIG. 4, the point assembly 26 includes a contact54 connected to ground an a contact 52 connected to one end 56 of asecond capacitor 58, the opposite end being grounded. Connection betweenthe contact 52 and the capacitor 58 defines a junction point 60. Thisjunction point is connected to a first end of primary winding 62, thelatter forming part of a second ignition coil (not shown). The oppositeend 64 of the primary winding is connected to the DC. voltage source 50.FIG. 4 further illustrates the circuit connections to the third pointassembly 28 comprising a first contact 66 connected to the firstmentioned junction point 47 connected to the first primary winding 46.Mating contact 68 is connected with the second mentioned junction point60 connected to the second mentioned primary winding 62.

Considering the operation of the circuit described in FIG. 4, it isnoted that during those times when dwell portions 22 on the cam 16engage both point assemblies 24 and 26, all point assemblies are closed.This causes a closed series circuit between voltage source 50, primary46, closed point assembly 24 and ground. Similarly, a series connectionis completed between voltage source 50, primary 62, point assembly 26and ground. Thus, both primary windings are energized. The cams 16 and30 are angularly positioned on the shaft relative to each other toeffectuate opening of point assembly 28 just a few degrees after theopening of either point assembly 24 or 26. FIG. 4 illustrates the stateof affairs when a high point 20 of cam 16 opens point assembly 24.However, instead of arc development across the points 36 and 38 of pointassembly 24 as occurs inconventional systems, the primay 46 is connectedto ground through the closed points of point assembly 28 and pointassembly 26 in series therewith. Should any arcing current be conductedacross the point assembly 28 when it subsequently opens, it will be in adirection from contact 66 to 68 and then to ground via closed pointsassembly 26. Accordingly, deenergization of primary winding 46 occurswith a commensurate collapse of the field associated therewith. This inturn causes an induced secondary voltage for spark plug firing as occursin conventional systems. As the high point on the cam 16 moves acrossthe cam follower of point assembly 24, and as the same occurs withrespect to cam 30 and its associated point assembly 28, all points arereturned to closed positions thereby causing reenergization of bothprimary windings 46 and 62. From the position illustrated in FIG. 4,rotation of cam 16 through 45 causes contact between a high point on cam16 and the cam follower of point assembly 26 thus forcing the points 52and 54 of that point assembly to open. However, a break in the primarywinding circuit connected in series with this point assembly does notoccur because a continuing connection between the primary winding 62 andground is maintained via the third point assembly 28 and point assembly24. Accordingly, when point assembly 26 opens no arcing occurs. However,as previously occurred in connection with the actuation of pointassembly 24, the third point assembly 28 opens several degrees after theopening of point assembly 26 thereby interrupting the energizing circuitof the primary winding 62. However, it is significant that any arcingcurrent conducted through the open points 28 now occurs from contact 68to contact 66. This arcing current direction is opposite from the arcingcurrent which occurred upon the opening of point assembly 24 ashereinbefore explained. Accordingly, in the steady state operation ofthe device, arcing current is alternately reversed across the contactsof point assembly 28 thereby preventing transfer of metal therebetween.As will be appreciated, u-pon deenergization of the primary winding 62,a field collapse occurs as explained in connection with the firstprimary winding 46 which results in an induced voltage in the respectivesecondary winding associated with primary winding 62 for firing of aspark plug.

In effect, the dual point assembly including point assemblies 24 and 26may be considered as current direction switching means for the thirdpoint assembly 28 for causing alternate deenergization of the primarywindings 46 and 62.

When installed, dual point assembly 24 and 26 shown in FIG. 1 is mountedupon the base plate 70. In a similar manner, the single point assembly28 is shown mounted upon base plate 72. It is noted that these baseplates may be of a suitable form utilized in conventional distributors.Therefore, it will be appreciated that the present invention may beemployed with conventional centrifugal and vacuum ignition advancemeans. All that is required is a common linking of base plate '70 and 72so that they experience simultaneous angular adjustment with respect tothe shaft 18 during mechanical ignition advance. The FIG. 1 furtherillustrates a distributor cap 74 which includes a number of peripherallydisposed conventional connection sockets 75 into which are insertedleads 76 for connection with respective spark plugs (not shown). Becausetwo primary coils are utilized, the distributor cap must include twoinput sockets 78. Such a construction is illustrated in Pat. No.2,278,679, issued Apr. 7, 1942 to K. Staub.

It is noted that the present device is adaptable for cooperation withmagneto ignition systems in a manner that should be obvious to one ofordinary skill in the art.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. In an ignition distributor system, a voltage source, first and secondignition coils connected in parallel to said voltage source, circuitbreaker means connected to said ignition coils for energization thereof,and current reversing means actuated in synchronism with said circuitbreaker means for alternately directing current therethrough in reversedirection during cyclic energization and deenergization of the ignitioncoils through the circuit breaker means, said current reversing meansincluding, rotating cam means, first and second switch meanssequentially actuated by said rotating cam means for opening normallyclosed circuits to the ignition coils, first and second capacitor meansrespectively connected to said first and second switch means in parallelwith the respective ignition coils and means electrically connectingsaid switch means to the circuit breaker means for shunting the openedcircuit to one of the ignition coils.

2. The combination of claim 1, wherein said circuit breaker meansincludes a breaker cam rotatably driven in synchronism with saidrotating cam means, third switch means actuated by the breaker cambetween sequential actuation of said first and second switch means, andmeans connecting said third switch means to said capacitor means forconducting current therethrough in opposite directions causingcyclically alternating deenergization of said ignition coils.

3. The system set forth in claim 1 wherein said rotating ca-m means ischaracterized by a peripheral surface having a plurality of equallyspaced switch actuating portions thereon, said breaker cam having anumber of equally spaced switch actuating portions thereon equal totwice the number of actuating portions on the rotating cam means causingsequential actuation of the respective switch means for preselected timeintervals.

4. An ignition distribution device having a housing and a rotating shaftdisposed therein, the combination comprising a first base plate mountedwithin said housing and having a central aperture through which saidshaft extends, first switch actuating means operatively connected withsaid shaft and disposed in spaced overlying relation with said baseplate, first and second switch means mounted in spaced relation on saidbase for sequential actuation by said first switch actuating means inresponse to rotation of the shaft, a second base plate attached to androtatable with said first base plate in spaced relation thereto, secondswitch actuating means operaively connected to said shaft in angularlyfixed relation to said first switch actuating means and third switchmeans mounted on said second base plate for actuation by said secondswitch actuating means in spaced time relation between actuation of saidfirst and second switch means.

5. The apparatus set forth in claim 4 together with first and secondignition coil primary windings, first and second capacitor means,circuit means interconnecting said primary windings to respective firstand second capacitor means and said aforementioned switch means forcausing cyclic alternating energization and deenergization of saidprimary windings.

6. The apparatus set forth in claim 4 together with ignition advancemeans operatively connected with said first and second base plates.

7. A distributor switch assembly comprising first and 6 second switchmeans alternately opening and closing, third switch means connected tothe first switch means for providing a momentary short circuit of thefirst switch means in response to opening of the first switch means toprevent arcing thereacross, means causing the opening of the thirdswitch means moments after alternating opening of the first and secondswitch means, means connecting the third switch means to the secondswitch means upon the opening of the first switch means to effect arcingcurrent flow across the third switch means in a first direction, themeans connecting the first and third switch means eflfe'cting a reversedarcing current flow when the first switch means is closed and the secondswitch means is opened, the connection between the second and thirdswitch means preventing arcing across the second switch means upon theopening thereof.

References Cited UNITED STATES PATENTS 1,487,002 3/1924 Adams 307102,195,612 4/1940 Carpenter 307-10 2,252,506 8/1941 Hartzell 30710 X2,718,564 9/1955 Collins et al.

ROBERT K. SCHAEFER, Primary Examiner T. B. JOIKE, Assistant Examiner US.Cl. X.R. 290 3s; 307437

